EF Core是Entity Framework Core的简称,是一个用于.NET平台的对象关系映射(ORM)框架。它提供了一种简单且强大的方式来操作数据库,包括将单个主键更改为复合主键。 要将单个主键更改为复合主键,可以按照以下步骤进行操作: 定义复合主键类:创建一个新的类,用于表示复合主键。该类应包含与原始主键相同的属性,并使用[...
Here is an example of fetching entities by composite using EF Core: 代码语言:txt 复制 // Entity model public class Entity { public int Key1 { get; set; } public int Key2 { get; set; } // Other properties } // DbContext public class MyDbContext : DbContext { public DbSet<Entity...
HasPrincipalKey也可以用于此目的,但这样做并不常见。 如果对HasForeignKey的调用中未指定任何属性,并且主键适用,则将其用作外键。 对于未按约定发现关系的导航、外键或必需/可选性质的情况,可以显式配置这些内容。 例如: C# protectedoverridevoidOnModelCreating(ModelBuilder modelBuilder){ modelBuilder.Entity<Blog>(...
EF core 2.0 Net core 2.0 错误: 因实体定义了多个key,打开数据库时程序报以下错误 An unhandled exception occurred while processing the request. InvalidOperationException: Entity type '***' has composite primary key defined with data annotations. To set composite primary key, use fluent API. 具体的...
EF Core 8.0 的重大變更 EF Core 9.0 的計劃 開始使用 版本及規劃 (藍圖) DbContext 設定與初始化 建立模型 概觀 實體類型 實體屬性 索引鍵 產生的值 陰影與索引子屬性 關聯性 概觀 一對多 一對一 多對多 外鍵和主體索引鍵 導航 慣例 對應屬性
}/*ef core api 中配置 modelBuilder.Entity<Course>() .Property(p => p.CourseId) .ValueGeneratedNever();*/ 2.DatabaseGeneratedOption.Identity 根据具体的数据库来生成,插入后值不可更新。 有identity rowversion guid 等 publicclassCourse {publicintCourseId {get;set; }publicstringCourseName {get;...
The[PrimaryKey]attribute was introduced in EF Core 7.0. Use the Fluent API in older versions. Value generation For non-composite numeric and GUID primary keys, EF Core sets up value generation for you by convention. For example, a numeric primary key in SQL Server is automatically set up to...
one or two issues that might be similar but I don't understand them well enough to consider them a match for this topic. Also I couldn't see this mentioned in the sparse information I could find about the upcoming EF Core 2.1 so I have to assume it's not included in the next ...
[PrimaryKey(nameof(State), nameof(LicensePlate))]internalclassCar{publicstringState {get;set; }publicstringLicensePlate {get;set; }publicstringMake {get;set; }publicstringModel {get;set; } } Value generation For non-composite numeric and GUID primary keys, EF Core sets up value generation for...
EF7 allows the default conventions used by EF Core to be removed. For example, it usually makes sense to create indexes for foreign key (FK) columns, and hence there is a built-in convention for this: ForeignKeyIndexConvention. However, indexes add overhead when updating rows, and it may...